PKT project

I got an incomplete PKT kit from century last week, it has all the main components for a gun, the bolt & carrier, trunnion, feed cover and pawl, back plate and sear housing. plus some misc other parts. best of all it was cheap!!

I am making a bbl out of a 1919 bbl, so far I have it chambered in 7.62 x 54R and fitted to the trunnion and shrunk on a sleeve for the gasblock. I still need to cut the locking lug. once the bbl is fitted I will make up a receiver from plate and set it up with a set of spade grips to make some sort of franken gun belt fed.

What is the rear barrel diameter where it slides into the front trunnion? I picked up a PKT kit from GunBroker and am considering using a Bren barrel. The PKT trunnion has an ID of 1.180" and the back of the Bren barrel has an OD of 1.168". (dial caliper measurements) The Bren diameter might be in the range that some heavy chrome plating would bring it up to specs.

the 1919 bbl is big enough to turn down to fit the trunnion, you can turn down the bren bbl and sleeve it to make it big enough. also the rear diameter on the trunnion is smaller than the front. the kit is at the shop, I will measure it tomorrow.
I have a reamer if you need to have the bbl rechambered.

I didn't think to check both ends of the trunnion. It's tapered shape is like a morse taper on a lathe. I think I will be sleeving the bren barrel and cutting a taper to match the internal dimensions. The is no clearance between the parts because of the taper.

I would still love to find out the measurements from an original PKM barrel. If anyone has one handy, please measure the OD at both ends of the receiver/barrel mating surface as well as the distance between the ends. That would give us the taper from an original PKM barrel. Then it can be compared to these PKT trunnions to see if they are identical.

I also realized tonight that a ring collar should be pressed on ahead of the taper to mate up with the two prongs extending from the front of the trunnion. They must be there to ensure the barrel is orientated correctly before the barrel lock is engaged. Cool engineering!

Looking good! I will be following with great interest. I have a couple other builds to get done and then will be starting something similar to yours.

I noticed you are using a .308 barrel for the 7.62x54 round. I was wondering if that would work well. I read somewhere that the Russians had rechambered .308 barrels to x54 in WW2. I was thinking they might have lengthened the throat when chambering them. It is said that when Ruger used .308 barrels on the mini-30 in 7.62x39 they lengthened the throat to swage the bullet more easily.